There are more than 100,000 new cases of colorectal carcinoma reported in the United States every year. Between 40 and 70% of patients with advanced colorectal cancer will have hepatic metastases; the majority of these will rely on chemotherapy for palliation of their disease. Regional infusion chemotherapy techniques have demonstrated improved response rates (55 to 85%) when compared to the 20% tumor response typically reported for systemic chemotherapy. Yet, these techniques may be associated with significant chemotherapy related side effects in greater than 50% of patients. At present, there is no satisfactory technique to predict those patients who will respond to therapy, or to rapidly identify those patients who are not responding after therapy has begun. The ability to predict and rapidly monitor tumor response to regional infusion chemotherapy would represent a major advance in decreasing the morbidity associated with this therapeutic approach. The objective of this proposal is to develop improved methods for monitoring the response to regional infusion chemotherapy of hepatic metastases in colorectal carcinoma through the integrated application of magnetic resonance imaging (MRI) and localized spectroscopic (MRS) techniques. The underlying concept for the approach we have chosen is that the integrated application of MRI/MRS will be more effective than either individual technique, and that understanding the relationship of morphology to metabolism will be critical to the successful integration of MRI and MRS. The interdisciplinary team includes an oncologic surgeon, a hepatopathologist, an MR spectroscopist as well as a gastrointestinal radiologist with expertise in MRI. This proposal includes a detailed study of the histopathologic basis of the signal intensity variations which may be identified on MRI of metastatic colorectal carcinoma to the liver, a study of the accuracy of MRI in the detection of metastatic colorectal carcinoma and the serial analysis of 31P MR spectra and MR images before, and during FUdR regional infusion chemotherapy. We will also serially study the steady state levels of the metabolites of FUdR during therapy utilizing 19F morphology and 31P spectra. These results will be compared to conventional indicators of response to therapy as noted in the proposal.